Rear derailleur

ABSTRACT

An embodiment of the invention provides an electromechanical rear derailleur for a bicycle including a base member that is configured to be coupled to a frame member of a bicycle. The derailleur includes a movable member and a link mechanism that movably couples the movable member to the base member. A motor is positioned at the movable member to move the movable member.

This application is a continuation of U.S. patent application Ser. No.15/183,913 filed Jun. 16, 2016, which is a division of U.S. patentapplication Ser. No. 13/691,391 filed Nov. 30, 2012, which claims thebenefit of U.S. Provisional Application No. 61/706,357 filed Sep. 27,2012.

BACKGROUND OF THE INVENTION

The invention relates to bicycle derailleurs. In particular, theinvention is directed to electromechanical rear derailleurs.

SUMMARY OF THE INVENTION

One aspect of the invention is an electronic derailleur for a bicyclehaving a base member for attachment to a frame member of the bicycle; amovable member; a linkage movably coupling the movable member to thebase member; and a transmission operable to move the movable memberrelative to the base member. The transmission has a PC board assembly; amotor electrically connected to the PC board assembly, the motorcomprising an output shaft rotatable about a motor axis; an output gearrotatable about an output axis; an encoder gear rotatable about anencoder axis responsive to rotation of the output shaft about the motoraxis; an encoder unit rotationally fixed with the encoder gear; and anencoder chip disposed between the PC board assembly and the encoderunit, wherein the encoder chip is configured to monitor an angularposition of the encoder unit.

Another aspect of the invention is an electronic derailleur for abicycle having a movable member configured to shift a chain of thebicycle; an output gear rotatable about an output axis; a drive armrotatably fixed to the output gear and configured to impart force to themovable member and another component of the electronic derailleur; andan encoder assembly configured to monitor an angular position of theoutput shaft. The encoder assembly has an encoder gear rotatable aboutan encoder axis responsive to rotation of the output gear about theoutput axis; an encoder unit fixed rotationally with the encoder gear;and an encoder chip disposed to overlap the encoder unit radiallyrelative to the encoder axis, wherein the encoder unit is freelyrotatable relative to the encoder chip.

Yet another aspect of the invention is a gear housing for an electronicderailleur having a motor having an output shaft; an output gearrotatable about an output axis responsive to rotation of the outputshaft; an encoder gear rotatable about an encoder axis responsive torotation of the output shaft; an encoder unit fixed nonrotatably withthe encoder gear; an encoder chip disposed axially between the encoderunit and the gear housing relative to the encoder axis. The encoder chipis configured to measure an angular position of the encoder unit; and alink pin is rotatably fixed to the output gear and configured to move alinkage of the electronic derailleur.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rear derailleur assembly installed on a bicycle.

FIG. 2 is a rear view of the rear derailleur assembly.

FIG. 3 is a view from E-E of the derailleur assembly of FIG. 2.

FIG. 4 is the rear derailleur assembly positioned with a cage assemblyof the derailleur in an extreme inboard position.

FIG. 5 is a section view along F-F of FIG. 3, with some parts omittedfor clarity.

FIG. 6 is a section view along G-G of FIG. 3, with some parts omittedfor clarity.

FIGS. 7A-D are side, front, bottom and isometric views of a power sourcefor the derailleur, respectively.

FIGS. 8A and 8B are two views showing the battery both installed andremoved from the rear derailleur assembly, with the cage assemblyomitted for clarity.

FIG. 9 is a section view along A-A of FIG. 2.

FIG. 10 is a side view of the battery, respectively, partially attachedand fully detached from the rear derailleur assembly.

FIG. 11 is a side view of the battery, respectively, partially attachedand fully detached from the rear derailleur assembly.

FIG. 12 is a perspective view of a flexible cable assembly.

FIG. 13 is a section view along H-H of FIG. 3.

FIG. 14 is a view of the moveable assembly with the cover removed toshow the motor and transmission.

FIG. 15 is a section view along C-C of FIG. 2, with some parts omittedfor clarity.

FIG. 16 is a section view along K-K of FIG. 14, with some parts omittedfor clarity.

FIG. 17 is a section view along J-J of FIG. 14, with some parts omittedfor clarity.

FIG. 18 is a section view along B-B of FIG. 2, with cage assemblyomitted for clarity.

FIG. 18A is the same view as FIG. 18, except that a clutch spring isshown in a partially actuated state.

FIG. 19 is the same view as FIG. 18, except that the clutch spring isshown in a fully actuated state.

FIG. 20 is a section view along D-D of FIG. 2 showing operation of thetravel limit assembly.

FIG. 21 is a section view along D-D of FIG. 2 showing operation of thetravel limit assembly.

FIG. 22 is an exploded view of the moveable assembly, with some partsomitted for clarity.

FIG. 23 is an oblique view of the rear derailleur assembly.

FIG. 24 is a side view of a front derailleur assembly.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention will herein be described with reference tothe drawings. It will be understood that the drawings and descriptionsset out herein are provided for illustration only and do not limit theinvention as defined by the claims appended hereto and any and all theirequivalents. For example, the terms “first” and “second,” “front” and“rear,” or “left” and “right” are used for the sake of clarity and notas terms of limitation. Moreover, the terms refer to bicycle mechanismsconventionally mounted to a bicycle and with the bicycle oriented andused in a standard fashion unless otherwise indicated.

Referring to FIGS. 1, 3, and 4, the basic structure of derailleurassembly 10 is generally similar to that of a conventional rearderailleur. The basic structure of the derailleur 10, generally shown inFig.1, which may be a rear derailleur and more particularly may be anelectromechanical rear derailleur or gear changer includes a base member1, which may be attached to bicycle frame 13 in a conventional manner,an outer link 3 and an inner link 4 pivotally attached to the basemember, and a moveable member or assembly 5 pivotally connected to theouter and inner links at an opposite end thereof to permit displacementof the moveable assembly. The outer link 3 and inner link 4 takentogether may be considered components of a linkage or link mechanism 92,for example a parallelogram-type link mechanism. Base member 1 is alsoknown as a b-knuckle and the moveable member 5 is also known as ap-knuckle. Cage assembly 8 may be pivotally connected to moveableassembly 5 in a conventional manner. Bicycle chain 12 is engaged withcog assembly 11 and cage assembly 8 in a conventional manner and isshifted from cog to cog by the movement of moveable assembly 5 and cageassembly 8 relative to base member 1.

Referring to FIGS. 1- 6, the link mechanism 92, referring first to FIG.5, interconnects the base member 1 and movable member 5 and is mountedtherebetween via a plurality of pivots or link pins as is well known.The linkage 92, in this embodiment, includes a first link pin 15 with athreaded portion 15 a that is threadably engaged with base member 1 in ablind hole. First link pin inner bushing 17 is received in a first holein outer link 3, and first link pin outer bushing 18 is received in asecond hole in outer link 3. First link pin inner bushing 17 and firstlink pin outer bushing 18 pivotally receive first link pin 15. Thus,outer link 3 is pivotally connected to base member 1.

Second link pin inner bushing 19 is received in a second hole in basemember 1. Second link pin outer bushing 20 is received in a third holein base member 1. Second link pin 16 is received in a first hole in aninner wall 4 b of inner link 4 and is also received in a second hole inan outer wall 4 c of inner link 4. Second link pin 16 is pivotallyreceived in second link pin inner bushing 19 and second link pin outerbushing 20. Second link pin retaining ring 21 engages a groove in secondlink pin 16 to retain the second link pin in position. Thus, inner link4 is pivotally connected to base member 1.

Referring now to FIG. 6, third link pin inner bushing 28 and third linkpin outer bushing 29 are received in holes in outer link 3. Third linkpin 26 is received in a hole in gear housing 6, and is pivotallyreceived in third link pin inner bushing 28 and third link pin outerbushing 29. Third link pin retaining ring 30 is engaged in a groove inthird link pin 26. Thus, gear housing 6 is pivotally connected to outerlink 3.

Referring to FIGS. 3, 6, and 17, cover 7 is fixed to gear housing 6 byfive screws 83, or any other suitable fasteners, which pass throughclearance holes in cover 7 and are threadably engaged with gear housing6.

Referring to FIG. 6, output gear inner bearing 33 is received in acounter bore in gear housing 6, and output gear outer bearing 34 isreceived in a counter bore in cover 7. Output gear inner O-ring 37 isreceived in a hole in gear housing 6 and output gear outer O-ring 38 isreceived in a hole in cover 7. Output gear 32 has a first tubularportion 32 b that extends through output gear inner bearing 33 andoutput gear inner O-ring 37, and a second tubular portion 32 c thatextends through output gear outer bearing 34 and output gear outerO-ring 38. Output gear 32 is located between an inner wall 4 b and anouter wall 4 c of inner link 4 and disposed about fourth link pin 27.Fourth link pin 27 is received in a third hole in inner wall 4 b ofinner link 4 and is also received in a fourth hole in outer wall 4 c ofinner link 4. Thus, gear housing 6 and cover 7 are pivotally connectedto inner link 4. Specifically, gear housing 6, cover 7, output gearinner bearing 33 and output gear outer bearing 34 are rotatable togetheras a unit relative to output gear 32, inner link 4, and fourth link pin27. Although output gear 32 and fourth link pin 27 are formed as twoseparate members, they may alternatively be formed together as oneunitary member in a single piece.

A fourth link pin retaining ring 31 is engaged in a groove in fourthlink pin 27. Inner thrust bearing 35 is coaxially located with firsttubular portion 32 b and is adjacent to an exterior surface of gearhousing 6. Outer thrust bearing 36 is coaxially located with secondtubular portion 32 c and is adjacent to an exterior surface of cover 7.Referring to FIGS. 6 and 18, projections 9 a of a drive arm 9 engagecastellations 32 a located at a distal end of first tubular portion 32 bof output gear 32. Thus, drive arm 9 is rotatably fixed to output gear32.

It will be understood that the linkage 92 may be held to the base member1 and movable member 5 with pivots and retaining means of other kindsand made pivotable by other than bearings and/or bushings as detailed inthe instant example.

Referring to FIGS. 6 and 14, gearbox gasket 25 is disposed in a groovein gear housing 6, and forms a water-tight seal between gear housing andcover 7.

Referring to FIGS. 7a-d , electrical power source 2, which may include arechargeable battery and may be of the lithium-polymer variety, ishoused within a battery housing 2 d. Terminals 2 c are provided on andrecessed slightly below a front surface of battery housing 2 d, and maybe co-molded into the battery housing. A barb or catch 2 a is located ona top surface of battery housing 2 d, and one or more projections 2 bare located on a bottom surface of the battery housing. Because of theconstruction (including the size and shape) of the housing 2 d,including barb 2 a and projections 2 b, the battery housing may beremovably attached to a derailleur and may be interchangeable between afront and rear derailleur. In this respect, a swappable battery 2 is asubstantial improvement over a single wired battery (powering twoderailleurs) should the one battery become discharged. When a pair ofbatteries 2 is used, with one battery installed in each of a front and arear derailleur, the charged battery could be installed in the rearderailleur and the rear derailleur would still be functional. Also, abattery could be installed in an emergency or shared with a ridingpartner. In particular, the housing 2 d may have a gross morphology thatcould be described as “laterally compressed” and which permits it to beinstalled on both front as well as rear derailleurs at least because theshape of the battery housing does not interfere with the user.

Referring to FIGS. 9-12, cable assembly 48 includes a flexible cable 47,which may be a two conductor cable sheathed in silicone, for example,like those manufactured by Cicoil® part number 969M101-28-2. A first endof flexible cable 47 terminates inside a boss on battery contactmounting plate 44. Two battery contacts 42, which may be made ofphosphor bronze, are each secured to battery contact mounting plate 44with a screw 43, for example, that passes through a hole in each batterycontact and may be threadably engaged with the battery contact mountingplate. Battery contacts 42 may be made of or plated with a corrosionresistant material such as gold. A first conductor 47 a of flexiblecable 47 is electrically connected by soldering or other appropriatemeans to an end of one battery contact 42, and a second conductor (notshown) of flexible cable is similarly connected to an end of the otherbattery contact. A battery seal 41 is mounted on battery contactmounting plate 44, and may be made of silicone rubber, for example. Asecond end of flexible cable 47 terminates inside contact housing 50.Contact housing 50 houses a connector 49, which may be a coaxialelement. Connector 49 may have two concentric conductors that are springloaded, for example, like those manufactured by TE Connectivity®, partnumber 1658260-1. The two conductors 47 a, 47 b of flexible cable 47 areelectrically connected to the two conductors of connector 49,respectively. An O-ring 51 is located in an O-ring gland in contacthousing 50.

Referring to FIG. 8B and FIG. 9, battery seal 41 together with batterycontact mounting plate 44 are located in a recess in base member 1. Ascrew 45 or other suitable fastener passes through a hole in batterycontact mounting plate 44 and threadably engages base member 1, therebyfixedly connecting battery contact mounting plate 44 to base member 1.The battery mounting plate 44 may be a separate part connectable to thebase member 1 as described or unitary (one-piece) with the base member.

Referring to FIG. 8A and FIG. 9, battery latch pin 40 is received by thebase member 1. Battery latch 39 has a corresponding thru-hole thatrotatably receives battery latch pin 40. Latch spring 46 is received ina blind hole in base member 1 and urges battery latch 39counterclockwise around battery latch pin 40 as shown in FIG. 9. Batterylatch 39 has a hooked end that engages barb 2 a of battery housing 2 d,and the urging force of latch spring 46 urges the hooked end of batterylatch against the surface of the battery housing. The latch 39 may beany suitable mechanism, catch device, engagement member, securing memberand so on, to retain and release the battery housing 2 d.

Referring to FIG. 8B and FIG. 9, base member 1 has two battery engagingholes 1 a. Referring to FIG. 9, projections 2 b of battery housing 2 dare engaged in corresponding battery engaging holes 1 a in base member1. Battery housing 2 d is held in an installed position that forcesbattery seal 41 to deform slightly, forming a water-tight seal againstthe front surface of the battery housing. The deformation of batteryseal 41 also causes the battery seal to exert an urging force againstthe front surface of battery housing 2 d, urging the surface to the leftin FIG. 9. This urging force, in turn, causes barb 2 a of batteryhousing 2 d to be urged to the left, against the hook of battery latch39, and causes projections 2 b of the battery housing to be urged to theleft, against battery engaging holes 1 a. In this manner, any playbetween battery housing 2 d and base member 1 is eliminated and thebattery is positively retained on rear derailleur assembly 10. Theinstalled position of battery housing 2 d also forces battery contacts42 to flex slightly against battery terminals 2 c, creating a pressurecontact between the battery contacts and the battery terminals that isconducive to the flow of electricity.

FIGS. 10 and 11 show the process by which the user can easily removebattery 2 from rear derailleur assembly 10. Referring to FIG. 10, theuser presses the right end of latch 39 downwards causing the latch torotate clockwise around latch pin 40 against the urging force of latchspring 46, which in turn causes the hooked end of the latch to rotateout of engagement with barb 2 a of battery housing 2 d. The user thenpivots battery housing 2 d counterclockwise around the engagement pointof projections 2 b and battery engaging holes 1 a. Referring now to FIG.11, when battery housing 2 d has been rotated sufficientlycounterclockwise, the user is able to lift the battery in a generallyupwards motion, causing projections 2 a of the battery housing todisengage from battery engaging holes 1 a of base member 1. In thismanner, battery housing 2 d is removed from rear derailleur assembly 10.By reversing this process, the user is able to easily reinstall battery2 in rear derailleur assembly 10.

Referring to FIG. 18, flexible cable assembly 48 passes through a holein base member 1 and extends between outer link 3 and inner link 4.Referring to FIGS. 13, 18, and 23, contact housing 50 of flexible cableassembly 48 is engaged in a complementary recess in gear housing 6. Twoscrews 88 pass through holes in contact housing 50 and are threadablyengaged in holes in gear housing 6, thereby fixedly connecting thecontact housing to the gear housing. Referring to FIG. 13, O-ring 51 isreceived in a bore in gear housing 6, and forms a water-tight sealbetween contact housing 50 and the gear housing.

Referring to FIGS. 13, 14, and 17, PC board assembly 52 is fixed to aninner surface of gear housing 6, such as with a screw 56. The PC boardassembly includes the various electronic elements and circuitry tocontrol the various functions of the derailleur 10. Additional locatingfeatures may be provided (not shown) in gear housing 6 to ensure that PCboard assembly 52 is accurately located in the gear housing. Referringto FIGS. 13 and 17, PC board assembly 52 and contact housing 50 arepositioned close enough to each other to force spring loaded connector49 to compress, creating a pressure contact between the connector 49 andthe PC board assembly that is conducive to the conduction ofelectricity. In this manner, flexible cable assembly 48 is in electricalcommunication with PC board assembly 52.

Referring to FIG. 13, motor 54 is preferably a DC motor and may beelectrically connected to PC board assembly 52 by a flexible cable 53.Motor 54 could instead be electrically connected to PC board assembly 52by other means, such as jumper wires or a flexible portion of the PCboard, for example. Referring to FIG. 22, motor mounting bracket 55 isfixed to gear housing 6 by three screws 87, or other suitable fasteners.Referring to FIGS. 13, 14, 15, and 22, ball bearing 71 is received in abore in motor mounting bracket 55 and a distal end of the output shaftof motor 54 is received by the ball bearing to be rotatably supportedthereby. Two screws 72, or other suitable fasteners, pass through holesin motor mounting bracket 55 and connect to motor 54, thereby securingthe motor to the motor mounting bracket. The motor 54 powers atransmission 90, which effects movement of the movable member 5 relativeto the base member 1 to effect positional changes of the derailleur 10.

The transmission 90 conveys the motion of the motor 54 into movement ofthe derailleur 10 and may include a worm 70 fixed to the output shaft ofthe motor by a press fit or by an adhesive, for example. Referring toFIGS. 15, 16, and 22, first pinion gear 58 and worm wheel 57 may bepress fit together in a conventional manner that is well known in thegear making industry, and are located in a cavity in motor mountingbracket 55 such that the worm wheel is meshed with worm 70. A thru-holeextends through both side walls of the cavity, concentric with thethru-hole in first pinion gear 58. A first pinion axle 73 is received inthe thru-hole in the cavity and is rotatably received in the thru-holein first pinion gear 58. A distal end of first pinion axle 73 extendsinto a blind hole in gear housing 6. One end of second pinion axle 74 isreceived in a blind hole in gear housing 6 and a second end of thesecond pinion axle is received in a hole in motor mounting block 55.Second pinion gear 60 and first spur gear 59 may be fixed together by apress fit and are rotatably received on second pinion axle 74. Firstspur gear 59 is meshed with first pinion gear 58. Referring to FIG. 16,a third pinion axle bearing 76 is pressed into a blind hole in gearhousing 6 and another third pinion axle bearing 76 is pressed into ablind hole in cover 7. The ends of third pinion axle 75 are received inthe third pinion axle bearings 76, respectively. Third pinion gear 62and second spur gear 61 are fixed together by a press fit and arerotatably received on third pinion axle 75. Second spur gear 61 ismeshed with second pinion gear 60 and third pinion gear 62 is meshedwith output gear 32. It will be understood that the transmission 90 andelements thereof may be in other forms, wherein operation of the motor54 through the transmission 90 results in movement of the derailleur 10.

Referring to FIGS. 14, 15 and 17, encoder gear axle 81 is received in ablind hole in cover 7. Magnet holder 80 and encoder gear 63 are fixedtogether by a press fit or may be injection molded as a single, unitarymember. Magnet 78 is fixed to magnet holder 80 by a press fit or by anadhesive and magnet spacer 79 is fixed to the magnet by a press fit orby an adhesive. Encoder gear 63 is meshed with output gear 32 and isrotatably connected to encoder gear axle 81. Thus, encoder gear 63,magnet holder 80, magnet 78, and magnet spacer 79 are all rotatabletogether as a unit around encoder gear axle 81. The encoder gear 63 ispart of the transmission 90 that is not in the load path between themotor 54 and the output gear 32.

Moreover, it is an aspect of an embodiment of the invention to size theencoder gear 63 such that the encoder gear revolves nearly 360 degreesin the full range of rotation performed by the output gear 32. In otherwords, if the output gear 32 rotates about 90 degrees in its full rangeof motion, the encoder gear can be sized to rotate about four times thatof the output gear, or about ¼ the diameter of the output gear ifdirectly attached thereto, and thus the encoder gear rotates an amountapproaching, but not exceeding about 360 degrees. This provides a highamount of resolution.

Referring to FIG. 17, encoder chip 77 may be a magnetic rotary encoderwith Hall Effect sensors, for example, the component manufactured byAustria Microsystems® part number AS5050, and is a component of PC boardassembly 52. The center of encoder chip 77 is substantially coaxial withmagnet 78. Thus the encoder may be an absolute encoder.

Again referring to FIGS. 14, 15 and 17, biasing gear axle 82 is receivedin a blind hole in cover 7. Biasing gear 64 is rotatably connected tobiasing gear axle 82 and is meshed with encoder gear 63. A first end ofbiasing gear spring 65 is connected to biasing gear 64 and a second endof the biasing gear spring is connected to a support feature (not shown)in cover 7. Biasing gear spring 65 urges biasing gear 64counterclockwise in FIG. 14 and the biasing gear in turn urges encodergear 63 clockwise in FIG. 14, eliminating any play or backlash betweenencoder gear 63 and output gear 32.

Referring to FIG. 18, clutch spring 22 includes clutch spring sleeve 23disposed on the second link pin 16. The coil parts of clutch spring 22are formed around clutch spring sleeve 23. A first leg 22 a of clutchspring 22 biases drive arm 9 against projection 4 a of inner link 4.Referring to FIG. 20, a second leg 22 b of clutch spring 22 engages asurface of inner link 4.

Again referring to FIG. 18, the coils of biasing spring 24 are disposedaround first link pin 15 and a first leg of the biasing spring urgesouter link 3 counterclockwise around the first link pin. A second leg(not shown) of biasing spring 24 engages a surface of base member 1.Because inner link 4 is operatively connected to outer link 3, the innerlink is likewise urged counterclockwise around second link pin 16.Because drive arm 9 is biased against projection 4 a of inner link 4,and the drive arm is non-rotatably engaged with output gear 32, theurging force of biasing spring 24 is transferred back through the drivegear train to worm 70, eliminating any play or backlash in the drivegear train.

Referring to FIGS. 14, 15, and 23, button 66 may be a momentaryelectrical switch or the like that is a component of PC board assembly52. Button actuator 67 may be a body of revolution that is received in athru-hole of gear housing 6. A seal member (not shown) is disposed in anO-ring gland (not shown) of button actuator 67 and forms a water-tightseal between the button actuator and gear housing 6. When buttonactuator 67 is pressed by the user, it moves axially until it actuatesbutton 66, changing its switching state. When button actuator 67 isreleased by the user, button 66 urges the actuator axially away from thebutton and the button reverts to its original switching state.

Button 66 may be used during the process of wirelessly pairing the rearderailleur assembly 10 with its corresponding user-operable shifters(not shown) and it may be used for other purposes in addition to this aswell, such as fine tuning the position of cage assembly 8 relative tocog assembly 11. It will be understood that the button 66 may be used bythe user to control a variety of operating parameters of the derailleurassembly 10.

LED 68 is a light-emitting diode that is a component of PC boardassembly 52. Lens 69 is substantially cylindrical in shape and is fixedin a thru-hole in gear housing 6 by either a press fit or an adhesive,for example, which provides a water-tight seal between the lens and thegear housing. Alternatively, a flexible seal could be provided betweenlens 69 and gear housing 6 in order to create a water-tight seal. Thefunction of LED 68 is to emit a light that passes through lens 69 and isvisible to the user in order to indicate a state of the rear derailleurassembly 10 to the user. LED 68 may be used during the process ofwirelessly pairing rear derailleur assembly 10 with its correspondingshifters (not shown), and it may be used for other purposes in additionto this, such as indicating to the user that battery 2 is low on power.It will be understood that any configuration of the LED is contemplatedwhereby the LED is observable by a user.

Referring to FIGS. 20 and 21, a travel limit or travel adjust mechanism14 includes a limit screw 84 with a threaded portion 84 a that isrotatably received in a thru-hole in barrel 85 and is threadably engagedwith a threaded hole in base member 1. Barrel 85 has a smooth,cylindrical outer surface and a non-round, e.g., square, inner surface85 b with a square cross section that is non-rotatably engaged with butaxially moveable relative to a corresponding or square portion 84 b oflimit screw 84, which may have a complementary square cross section.Limit screw spring 86 is a compression spring disposed around threadedportion 84 a that urges barrel 85 substantially to the right in FIGS. 20and 21, against a surface of base member 1. When the user rotates barrel85 by hand, limit screw 84 also rotates and simultaneously moves axiallyrelative to the barrel due its threaded engagement with base member 1.Multiple ramped recesses 85 a in an end surface of barrel 85 engagecomplementary projections (not shown) on a surface of base member 1,creating a detenting action that retains the barrel in the position inwhich the user sets it.

In both FIGS. 20 and 21, inner link 4 is shown contacting the end oflimit screw 84 and further clockwise rotation of the inner link aroundsecond link pin 16 is prevented by limit screw 84. The function of limitscrew 84 is to limit the rotation of inner link 4 relative to basemember 1 in order to ensure that cage assembly 8 does not collide withthe spokes of the wheel of the bicycle on which rear derailleur assembly10 is installed. Comparing FIGS. 20 and 21, it can be seen that in FIG.20 limit screw 84 is relatively retracted allowing a relatively largeamount of rotation of inner link 4 relative to base member 1, while inFIG. 21 the limit screw protrudes more from the base member, limitingthe rotation of the inner link to a greater degree. Whereas traditionalderailleur limit screws are actuated with a tool such as a hex wrenchthat allows the user to apply a relatively large amount of torque to thelimit screw, the smooth, cylindrical outer surface of barrel 85 limitsthe amount of torque that the user can apply since the smooth surface ofthe barrel will slip between the user's fingers at a relatively lowtorque threshold. The advantage of this arrangement compared totraditional limit screws is that it greatly limits the amount of forcethat the limit screw can exert on the parallelogram of the rearderailleur assembly 10 and therefore greatly limits the amount of forcethat is transferred to the transmission 90 minimizing the possibility ofdamage to gear teeth or other components.

PC board assembly 52 includes a transceiver (not shown) whereintransceiver is a generic term describing a device that can both transmitand receive signals wirelessly. The transceiver periodically listens forwireless shift commands from shift controls, which may be actuated byactuators positioned on or in control hoods of a handlebar of thebicycle (not shown). When a wireless shift command is received by thetransceiver, the transceiver forwards the shift command to a processor,and a PID control loop is used to manage a flow of electrical power frombattery 2 through flexible cable assembly 48 and the PC board assemblyto motor 54. The output shaft of motor 54 rotates either clockwise orcounterclockwise depending on whether an upshift or a downshift isrequested and causes the actuation of the transmission 90. The resultingrotation of worm 70 causes rotation of worm wheel 57, which rotatestogether with first pinion gear 58 to rotate first spur gear 59, whichrotates together with second pinion gear 60 to rotate second spur gear61, which rotates together with third pinion gear 62 to rotate outputgear 32.

In the case that a downshift i.e. a shift to a larger cog is desired,castellations 32 a of output gear 32 rotate drive arm 9 clockwise aroundfourth link pin 27 in FIG. 18, which in turn drives projection 4 a alongwith inner link 4 clockwise, causing moveable assembly 5 and cageassembly 8 to move inboard towards the larger cogs. As cage assembly 8moves inboard, encoder chip 77 along with magnet 78 are used to monitorthe angular position of encoder gear 63, and when the encoder gearposition corresponding to the desired cog has been reached, power to themotor 54 is shut off, as cage assembly 8 is aligned with the desiredcog. As previously described, biasing spring 24 eliminates any play orbacklash in the drive gear train, ensuring that cage assembly 8 isaccurately and repeatably positioned.

In the case that an upshift i.e. a shift to a smaller cog is desired,castellations 32 a of output gear 32 rotate drive arm 9 counterclockwisearound fourth link pin 27 in FIG. 18, which in turn drives clutch spring22 along with inner link 4 counterclockwise, causing moveable assembly 5and cage assembly 8 to move outboard towards the smaller cogs. As cageassembly 8 moves outboard, encoder chip 77 along with magnet 78 are usedto monitor the position of encoder gear 63, and when the encoder gearposition corresponding to the desired cog has been reached, power to themotor is shut off, as cage assembly 8 is aligned with the desired cog.As previously described, biasing spring 24 eliminates any play orbacklash in the drive gear train, ensuring that cage assembly 8 isaccurately and repeatably positioned.

Due to the presence of worm 70 in the drive train, the drive train isnot reversible. In other words, although rotation of worm 70 can driveworm wheel 57, the worm wheel cannot drive the worm, due to friction. Aconsequence of this is that if an external force e.g. in the event of acrash or other impact is experienced by moveable assembly 5 or outerlink 3, that force will be transferred through drive arm 9 to gears ofthe transmission 90 drive train, and one or more of the gears orassociated components may break or be damaged. In order to prevent suchbreakage or damage from happening, the following system may be in place.When moveable assembly 5 or outer link 3 experiences an excessiveexternal force e.g. from a crash directed in the inboard direction,drive arm 9 overcomes the preload of first leg 22 a of clutch spring 22and deflects the first leg as shown in FIG. 18A. Thus, the energy of theexternal force is absorbed by clutch spring 22, and moveable assembly 5moves relative to base member 1 without any rotation of drive arm 9relative to the moveable assembly. In this state, guard rails 9 b oneither side of first leg 22 a of clutch spring 22 prevent the first legfrom becoming disengaged from drive arm 9. When the external force isremoved from rear derailleur assembly 10, the urging force of first leg22 a of clutch spring 22 moves drive arm 9 along with moveable assembly5 back to the position shown in FIG. 18. In extreme cases of externalforce applied to moveable assembly 5 and outer link 3, drive arm 9 maycause first leg 22 a of clutch spring 22 to deflect as far as is shownin FIG. 19. In this state, hard stop 9 c of drive arm 9 abuts projection4 a of inner link 4. When the external force is removed from rearderailleur assembly 10, the urging force of first leg 22 a of clutchspring 22 is not able to move drive arm 9 and moveable assembly 5 backto the position shown in FIG. 18, and the user must manually move themoveable assembly back to the position shown in FIG. 18a , at whichpoint the first leg will be able to move the drive arm and the moveableassembly back to the position shown in FIG. 18.

After a period of inactivity, i.e. no shift commands received, most ofthe electronic systems of PC board assembly 52 may shut down to conservepower. During this time the transceiver is shut down and cannot receiveshift commands. A vibration sensor (not shown) is provided on PC boardassembly 52 that, when it detects vibration, causes the electronicsystems of PC board assembly, including the transceiver, to turn onagain. The vibrations that naturally occur while riding the bicycle,which can be caused by the interaction of the road with the bicycle andby the interaction of the bicycle's various components with each other,are strong enough to activate the vibration sensor and prevent theelectronic systems of PC board assembly 52 from shutting down. But whenthe bicycle is not being ridden, i.e. parked, the vibration sensor doesnot detect any vibration and most of the electronic systems of PC boardassembly 52 shut down to conserve power. As soon as the rider makescontact with the bicycle, the resulting vibration activates thevibration sensor, turning the electronic systems on again. The vibrationsensor may be, for example, a mems type 3 axis accelerometer, such as aFreescale® MMA7660FC or MMA845IQ, or an omnidirectional chatter-typesensor such as a Signal Quest SQ-MIN-200. It will be understood that theapplication to the system described above of the vibration sensor to bewithin the ability of an artisan of ordinary ability.

Turning to FIG. 24, a front derailleur assembly 110 is shown including abattery 2 and battery housing 2 d. The front derailleur assembly 110includes a base member 101 to which the battery housing 2 d is removablyattached. A linkage 192 is movably attached to the base member 101. Acage assembly 199 is attached to the linkage 192. Because the batteryhousing 2 d is shaped and sized to be attached to either a front or rearderailleur, the battery can be interchangeable therebetween. It will beunderstood that the base member 101 of the illustrated front derailleurassembly 110 will include a means for attaching the battery housing 2 dand means for providing electrical connection that is similar or thesame as that detailed with respect to the rear derailleur shown anddiscussed herein.

While this invention has been described by reference to particularembodiments, it should be understood that numerous changes could be madewithin the spirit and scope of the inventive concepts described.Accordingly, it is intended that the invention not be limited to thedisclosed embodiment, but that it have the full scope permitted by thelanguage of the following claims.

The invention claimed is:
 1. An electronic derailleur for a bicycle,comprising: a base member for attachment to a frame member of thebicycle; a movable member; a linkage movably coupling the movable memberto the base member; and a transmission operable to move the movablemember relative to the base member, the transmission comprising: a PCboard assembly; a motor electrically connected to the PC board assembly,the motor comprising an output shaft rotatable about a motor axis; anoutput gear rotatable about an output axis; an encoder gear rotatableabout an encoder axis responsive to rotation of the output shaft aboutthe motor axis; an encoder unit rotationally fixed with the encodergear; and an encoder chip disposed between the PC board assembly and theencoder unit, wherein the encoder chip is configured to monitor anangular position of the encoder unit.
 2. The electronic derailleur ofclaim 1, wherein the encoder chip is further disposed on the PC board.3. The electronic derailleur of claim 2, wherein the encoder chip isfurther disposed in an axially overlapping manner with the encoder unitrelative to the encoder axis.
 4. The electronic derailleur of claim 1,wherein the transmission is disposed on the movable member.
 5. Theelectronic derailleur of claim 1, wherein the output axis and theencoder axis are substantially parallel.
 6. The electronic derailleur ofclaim 5, wherein the encoder axis and the output axis lie in a planeorthogonal to the PC board.
 7. The electronic derailleur of claim 5,wherein the encoder gear rotates counterclockwise about the encoder axisresponsive to clockwise rotation of the output shaft about the motoraxis.
 8. The electronic derailleur of claim 5, wherein the encoder axisand the output axis are not coaxial.
 9. The electronic derailleur ofclaim 1, further comprising a drive arm rotationally fixed with theoutput gear and configured to impart force to the base member and themovable member.
 10. The electronic derailleur of claim 9, wherein theangular position of the encoder unit is indicative of a position of themovable member relative to the base member.
 11. The electronicderailleur of claim 1, wherein the encoder unit comprises a magnet. 12.An electronic derailleur for a bicycle, comprising: a movable memberconfigured to shift a chain of the bicycle; an output gear rotatableabout an output axis; a drive arm rotatably fixed with the output gearand configured to impart force to the movable member and anothercomponent of the electronic derailleur; and an encoder assemblyconfigured to monitor an angular position of the output shaft, theencoder assembly comprising: an encoder gear rotatable about an encoderaxis responsive to rotation of the output gear about the output axis; anencoder unit fixed rotationally with the encoder gear; and an encoderchip disposed to overlap the encoder unit radially relative to theencoder axis, wherein the encoder unit is freely rotatable relative tothe encoder chip.
 13. The electronic derailleur of claim 12, wherein theencoder chip is part of a PC board assembly.
 14. The electronicderailleur of claim 12, wherein the PC board assembly is axially closerto the encoder unit than to the encoder gear relative to the encoderaxis.
 15. The electronic derailleur of claim 12, wherein the output axisis substantially parallel to the encoder axis.
 16. A gear housing for anelectronic derailleur, comprising: a motor having an output shaft; anoutput gear rotatable about an output axis responsive to rotation of theoutput shaft; an encoder gear rotatable about an encoder axis responsiveto rotation of the output shaft; an encoder unit fixed nonrotatably withthe encoder gear; an encoder chip disposed axially between the encoderunit and the gear housing relative to the encoder axis, the encoder chipconfigured to measure an angular position of the encoder unit; and alink pin rotatably fixed to the output gear and configured to move alinkage of the electronic derailleur.
 17. The gear housing of claim 16,wherein the encoder chip is disposed on a PC board fixed to the gearhousing.
 18. The gear housing of claim 16, wherein the PC board isaxially spaced apart from the encoder unit relative to the encoder axis.19. The gear housing of claim 16, wherein the encoder gear cannottransmit an urging force from the output shaft of the motor to theoutput gear.
 20. The gear housing of claim 19, wherein the encoder gearmoves responsive to the urging force transferred from the output shaftto the output gear.